无法弄清楚为什么res.json（）没有在单元测试覆盖率Angular中命中

Question

So I have a Unit Test Coverage being tracked by the karma-coverage-instanbul-reporter, when I look at the coverage report though, the:

.map(res => res.json())

portion of all of my Providers is never hit in the test. But I do have tests for those Providers, and am verifying that I'm getting a response.

Here is an example of on the functions I'm testing:

public getCampaigns(): Observable<CampaignsResponse> {
  return this.http.get(this.campaignsUrl).map(res => res.json());
}

Here is the test for this function:

describe("getCampaigns", () => {
  it("should return an Observable<CampaignsResponse>",
    inject([CampaignsService, MockBackend], (service: CampaignsService, mockBackend: MockBackend) => {
      // arrange
      mockBackend.connections.subscribe((connection: any) => {
        connection.mockBackend(new Response(new ResponseOptions({
          body: JSON.stringify(mockCampaigns),
        })));
      });

      // act
      service.getCampaigns().subscribe((campaigns) => {
        // assert
        expect(campaigns.campaigns.length).toEqual(1);
   expect(campaigns.campaigns[0].id).toEqual(mockCampaigns.campaigns[0].id);
      expect(campaigns.campaigns[0].channelID).toEqual(mockCampaigns.campaigns[0].channelID);
      expect(campaigns.campaigns[0].name).toEqual(mockCampaigns.campaigns[0].name);
      expect(campaigns.campaigns[0].active).toEqual(mockCampaigns.campaigns[0].active);
      expect(campaigns.campaigns[0].createdAt).toEqual(mockCampaigns.campaigns[0].createdAt);
      expect(campaigns.campaigns[0].updatedAt).toEqual(mockCampaigns.campaigns[0].updatedAt);
    });
}));

});

But according to my test coverage res.json() is never hit inside the map function.

Does anyone have any ideas on why that might be? Is it possible that the Coverage report is just wrong or is mapping the code incorrectly back to TypeScript?

Answer 1

Your connection has the type MockConnection instead of any , and MockConnection does not have a mockBackend property. Instead, it has a mockRespond . https://angular.io/docs/ts/latest/api/http/testing/index/MockConnection-class.html

Try modifying the test like this:

// arrange
mockBackend.connections.subscribe((connection: MockConnection) => {
  connection.mockRespond(new Response(new ResponseOptions({
    body: JSON.stringify(mockCampaigns),
  })));
});